Electromagnetically-operated device



H. R. CANFIELD. ELECTROMAGNETIC-ALLY OPERATED DEVICE. APPLICATION FILED APR- 9. 1917. RENEWED MAY 17. 19520.

Patented Oct. 5, 1920.

IN VEN T0 1?. flQIQ UanfiE/O W11 am A TTO RN E Y.

UNITED STATES HARRY R. CANFIELD, (3F CLEVELAND, O

ASS-IG-NQR TO THE ELECTRIC CON- TROLLEB & MANUFACTURING CGM'PANQ, OF CLEVELAND, OHIO, A CORPORA- TION OF OHIO.

ELECTBOIIIAGIQETICALLY-OPERATED DEVICE.

Specification of Letters Patent.

Patented Oct. 5, 1920.

A u ation fi led April 9, 1217, Serial No. 160,619. Renewed May 17, 1920. Serial No. 382,084.

To all 207207) it may concern Be it known that I, HARRY R. CaNrInLD, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented new and useful Improvements in Electromagnetically-Operated Devices, of which the following is a specification.

This invention relates to electromagnetically operated devices, and particularly to magnetically operated switches.

The principal object of my invention is to provide an electromagnetic switch, which, when its operating winding is unenergized, is mechanically biased to open position; and in which, when the winding is energized with current above a predetermined value, the mechanical bias holding the switch open is removed, and a second mechanical bias tending to close the switch is prevented from closing it by the magnetism from the winding; and in which, when the current in the winding is below or is reduced to a point below the predetermined value, the magnetism is insuflicient to hold the switch open and the second mechanical bias closes the switch and holds it closed. Other objects will be apparent.

In the drawings, Figures 1, 2 and 3 show side views, partly in section and partly broken away, of three of the many forms in which my invention may be embodied.

Referring to Fig. 1 of the drawings, the energizing winding is shown at 1. The magnetic circuit energized by the winding 1 consists of the stationary U-shaped main frame 2 having the right leg 3 and the left leg 4; the shunt member 5 of restricted cross section and limited magnetic carrying capacity connecting the ends of the legs 3 and 4; the plunger 6 enlarged at its lower end to increase its weight; and the magnetizable switch-arm or switch-member 7 pivotally supported at 20 and having pole faces 8, 9, and 10. Four magnetic air aps are provided, the gap 11 between the upper end of the leg 4 and the pole face 8, the gap 12 between the upper end of the leg 3 and the pole face 10, the gap 13 between the upper surface of the magnetic shunt 5 and the pole face 9, and the gap 1 1 between the lower surface of the shunt 5 and the upper end of the plunger 6. The restricted shunt 5 is provided with two damning rings or sleeves 32, of low electrical resistance. The plunger 6 1s movable vertically in the winding, and is normally suspended in position by the stem 10 which is driven into the upper end thereof, passes upwardly through a perforation 16 in the shunt 5 and through hole 17 in the switch-arm 7, and terminates nthe head 18, the under side thereof resting on the shoulder 19 on the arm. The we ght of the plunger tends to rotate the switch-arm 7 about its pivotal support 20 in the clockwise direction, its movement in this direction being limited by the adjustable screw 21 screwed into the end of the switch-arm and resting upon the upper end of the leg 3. By adjusting the screw 21, the normal position of the switch-arm 7, and hence the relative sizes of the air gaps 11, 12, 13, and 14 may be adjusted.

The pivotal support 20 of the switch-arm is carried by the stationary bracket 22. The compression spring 23, one end of which is stationary, is arranged to press on the swltch-arm '7 at 2% along a line of action below the center ofthe pivot 20, tending to rotate the switch-arm 7 in the counter clockwise direction, but normally prevented therefrom by the preponderating weight of the plunger 6. '1

.Under certain conditions, to be described later, the magnetic flux generated by the winding lifts the plunger 6, which thereby removes its weight from the arm 7, and permits the spring 23 to rotate the arm 7 in the counter clockwise direction. The counter clockwise movement of the switch-arm '7 causes the contact 27 on the switch-arm to engage the flexible brush or contact 28 mounted on the stationary contact-support 29, the counter clockwise movement being finally limited by the engagement of the stop 25 on the arm 7 with the stop 26 on the bracket 22. The contact support 29 and the bracket 22 are provided, respectively, with the studs 30 and 31, to which electrical connections may be made, so that the engagement of the contacts 27 and 28 may be used to close an electric circuit.

The operation of my invention as shown in Fig. 1 is as follows: When the winding 1 is energized with current, the flux generated therein flows, say, upwardly, in the plunger 6, and across the gap 14, where it divides; and, if the energizing current be below a predetermined value, approrimately equal parts of the flux flow to the right and to the left through the restricted shunt 5,

downwardly through the legs 3 and 1 of the frame 2 to the lower end of the plunger. The magnetic pull in the gap 14 hfts the plunger 6 from the arm 7, which under the action of the spr ng 23 rotates the switcharm' 7 counter clockwise. and closes the switch contacts 27 and 28. If, however, the energizlng current in the wlndlng be above the. predetermined value, the flux flowing, upwardly 1n. the plunger across-the gap 1 will, divide into four parts, one part going to the right and another part to the left through the. restricted shunt 5, and downwardly through thelegs 3 and 4, s before.

Themagnetic capacity of the shunt obeing. satisfie d the. other part flows across thegap 13. into the pole face '9 and there divides,

one portion. going to the right through the arm. 7 to. the pole face 10, across the gap 12 and: downwardly through the leg 3, and the other portion going, tothe left, through the arm. 7 to the pole face 8, across the gap 11 and downward'ly through the leg 4. The; magnetic pull in the gap'14c lifts the plunger 6, as. before, but now the magnetic pull acrossthegaps 12,13, and 11 is sufficient to hold the arm 7 1n itsnormal position against the counter clockwise torque due to the .spring 23. If now the current be reduced to-a point below the predetermined value,

' thetotahflnx in the circuit isreduced to such. avalue that substantially all of the flux flowing: upwardly in the plunger 6 flOWSJIl the restricted shunt 5, and little or none in the gapsrl2, 13, and 11,,s0'that,. wh1le the fiuxissufficient to. hold up the plunger 6.

the magnetic pull holding the switch-arm-in its normal positlon is reduced to sucha value thatthe spring. 23 can rotate'it in'the'counT ter clockwise direction and close the switch, as abovedescrlbed. I

-Upon energizing the winding with cur rent above thepredetermined value, the flux in themagnetic circuit builds. up from zero to the value which locks the switch open, as

above described, and: in. so doing passes value,- the damping rings or sl'e'eves 32 are provided onthe shunt 5 'tochoke or deflect the flux. out of the shunt andinto the gap: 13,.whereby substantially all of the flux en;

erts a clockwise pull on the switch-arm. After the flux reaches its final; orstable value, the choking effect of the 'rings or' sleeves 32 ceases and a part oftheflux flows 'in the shunt 5, leaving'inthe gaps 11, 12. and 13 only. sufficient flux tohold the switch arm in its normal position; and when the current in the winding is reduced to'a point below the predetermined value, the flux in the gaps 11, 12, and 13 becomes insufficient to hold the switch-arm against the torque of the spring 23. V

After the switch has been. closed, it. re mainsclosed as long asthe winding is energized sufliciently to hold the plunger in its upper position. WVhen'the winding is de energized, or the current is reduced to a certain minimum, the pliinger 6 falls, and the head 18, striking the shoulder 19,,rotatestne arm 7. ina clockwise direction against the pressure of the spring 23, and opens the switch contacts. 7

In the form of my invention shown in Fig.2, I employ a form of magnetic circuit. somewhat different fromthat in Fig. 1. 1

j provide the stationary Ushaped mainframe tween the upper end of theleg 3- and the:

pole; face 10, the. gap 12 between theupper surface ofthepole piece33 and the pole, face 10,thegapl1. between the upper surface of: the'pole piece 33 andthe pole. faceS, and the Five air gap 11 between thepoleface-Sand the. up- 7 per. end ofthelegt. The stem 15 passes; through the perforation 40. inthe, pole piece 33. The other parts of this form, of my invention are the same as the correspond ingfparts in Fig. 1. a

The operation of the form of-my inventionshown in Fig. 2'isias follows: lVhen the winding, is, energized with current below a predetermined-value, the fluX flows, say, upwardly. in the plunger 6, acrossthe gap 14 into-the pole; piece 33; andthere divides. part going to the right through the pole piece 33, the gap-12%.the pole face 10, the arm 7,.the-gap 12, and the leg 3 to the lower end of theplunger; and the other partgoing; to the left through the; pole piece-33, the-gap. 11 thepole-face 8-, the switcharm 7, the

gap 11, and the leg} 4 to the lower end. of i the.- plunger. Thefl'ur, in the gap 14 liftstheplunger 6,. but the flux in the gaps; 11', 11 12,;and12" is insufficient to hold the switch-arm in its normal position, and the spring 23' causes the arm toclosethe switch. a

If, however, the winding be energized with current abovethepredetermined: value, the

plunger will be lifted as before, but. now,

the flux. across the gaps ll; 11?, 12, and 12 willibe sufficiently strong to hold the switch.- arm in its normal position against: thepressure, of the springi23; If now the current be lowered. to a point below thepredeter: mined value,,.the fluxzwill he reduced. to 7 such an amount that the pull in the gaps 11, 11, 12, and 12 will be insufficient to hold the switch-arm in its normal position, but sufficient to hold the plunger in its lifted position, and the switch will be closed by the spring 23. hen the winding is deenergized, or the current reduced to a certain minimum, the plunger 6 falls and rotates the switch-arm clockwise and opens the switch contacts.

In the form of my invention shown in Fig. 3, the magnetic circuit has the stationary right leg 3, the stationary left leg 4, the movable plunger 6 carrying at its lower end the armature 35 integral therewith, and the magnetic switch-arm 7 having the pole faces 8, 9, and 10. Non-magnetic spacers 36 and 37 are provided, connecting the upper and the lower ends respectively of the legs 3 and 4, and rigidly holding the legs in their relative positions shown. The stem 15 passes upwardly through the hole 41 in the spacer 36, and the plunger 6 is normally suspended, as in the forms shown in Figs. 1 and 2. The lower end of the plunger 6 passes through the hole 42 in the spacer 37. The other parts of this form are the same as the corresponding parts in Figs. 1 and 2. Five air gaps are provided; the gap 1 1 between the upper end of the plunger 6 and the pole face 9 on the switch-arm 7, the gap 12 between the upper end of the leg 3 and the pole face 10 of the switch-arm, the gap 11 between the upper end of the leg 1 and the pole face 8 of the switcharm, the gap 38 between the lower end of the leg 3 and the armature 35, and the gap 39 between the lower end of the leg 4 and the armature 35.

The operation of the form of my invention shown in Fig. 3 is as follows: When the winding is energized with current below the predetermined value, the flux flows, say, upwardly in the plunger 6, across the gap'li, into the pole face 9, and there divides, one part flowing to the right through the arm 7, the pole face 10, the gap 12, the leg 3, the gap 38 and the armature 35 to the lower end of the plunger 6, and the other part flowing to the left through the arm 7, the pole face 8, the gap 11, the leg 4, the gap 39 and the armature 35 to the lower end of the plunger 6. The flux in the gaps 14, 38 and 39, and particularly that in the latter two, lifts the plunger and armature 35 together, the armature being thereafter held up by the closed gaps 38 and 39. The flux in thegaps 11. 12, and 14;, however, being insuficient to hold the switch-arm against the force of the spring 23, the latter causes the switch to close. If the winding, however, be energized with current above the predetermined value, the plunger and the armature will be lifted, as before, but now the flux in the gaps 11, 12 and 14: will hold the arm 7 in its normal position, preventing the switch from being closed. If now the current be reduced to a point below the predetermined value, the flux in the gaps 38 and 39 will hold the plunger in its lifted position, but the flux in the gaps 11, 12 and 14 will. be reduced to such a value that the spring 23 will be able to move the switcharm and close the switch. V hen the winding is deenergized, the plunger 6 and the armature 35 falls and the switch-arm is pulled open, as in the other forms.

As is well known, switches having the general operating characteristics described herein may be used for controlling the starting resistance of an electric motor, and it is therefore not deemed necessary to show herein an application of my invention to practical uses. It is apparent that the switches herein described may be substituted for the accelerating switches shown in many other motor control systems. For example my switches may be readily substituted for the accelerating switches shown in my application Serial Number 583,000, or in Halls Patent, No. 1,197,58d.

My invention is not limited in its application to motor control or motor starting purposes. Many changes and modifications other than those shown may be made without departing from the spirit of my invention;- for example, I have shown three forms of magnetic circuit by which the desired char.v acteristics are developed in respect to current conditions in the winding, but it is apparent that other forms of magnetic circuit may be employed. While I have shown a mechanical bias which moves the switch contacts to the closed position and holds them closed, such bias being produced by a spring acting on one side of the center of rotation of the switch-arm, it is apparent hat other means employing either springs or gravity, or their equivalent, acting without the necessity of magnetic assistance from the winding, may be employed. Other changes and modifications may be made without departing from the spirit of my invention.

I claim:

1. A controlling device for electric circuits, comprising a winding, a movable switch member, means for normally biasing it to open position, and means whereby the bias is removed and whereby the winding holds the switch member in open position when the current is above a predetermined value and permits it to be closed and held closed without magnetic assistance from the winding when the current is below the predetermined value.

2. A controlling device for electric circuits, comprising a winding, a movable switch member, means for normally biasing it to open position, and means whereby the Winding removes the said bias and When the current is above'a predetermmed value holds the switch member in open position:

' against a second bias tending to close it, and

whereby the Winding permits 'thB"SWll3Cl1 member'to be closed and-held. closed by the second bias Without magnetic assistance .from1theWinding When the current 15 below the. predetermined value.

8. A controllingi device for electric cir cuits, comprising a Winding, a movable switch member, means for-normally biasto closed position but having less strength 15 than the first biasing-means, and means whereby the-winding removes the first bias and holds the switch member in the'open position against the second bias when the current is above a predetermined valueand whereby the windingpermits the switch member to be closed and held closed by the second bias Without magnetic assistance from the Winding When the current is below the'predetermined value; 1 I

Signed at Cleveland, Ohio, this 5th day of April, 1917. V v Q HARRY R. CANFIELD. 

